The present invention relates generally to the combinatorial synthesis of [3,5,7]-1H-imidazo[1,5-a]imidazol-2(3H)-one derivatives. More specifically, the invention provides novel [3,5,7]-1H-imidazo[1,5-a]imidazol-2(3H)-one compounds as well as novel combinatorial libraries comprised of many such compounds, and methods of synthesizing the libraries.
The process of discovering new therapeutically active compounds for a given indication involves the screening of all compounds from available compound collections. From the compounds tested one or more structure(s) is selected as a promising lead. A large number of related analogs are then synthesized to develop a structure-activity relation-ship and select one or more optimal compounds. With traditional one-at-a-time synthesis and biological testing of analogs, this optimization process is long and labor intensive.
Adding significant numbers of new structures to the compound collections used in the initial screening step of the discovery and optimization process cannot be accomplished with traditional one-at-a-time synthesis methods, except over a time frame of months or even years. Faster methods are needed that permit the preparation of up to thousands of related compounds in a matter of days or a few weeks. This need is particularly evident when it comes to synthesizing more complex compounds, such as the [3,5,7]-1H-imidazo[1,5-a]imidazol-2(3H)-one compounds of the present invention.
Solid-phase techniques for the synthesis of peptides have been extensively developed and combinatorial libraries of peptides have been prepared with great success. During the past four years there has been substantial development of chemically synthesized combinatorial libraries (SCLs) made up of peptides.
The preparation and use of synthetic peptide combinatorial libraries has been described for example by Dooley in U.S. Pat. No. 5,367,053; Huebner in U.S. Pat. No. 5,182,366; Appel et al in WO PCt 92/09300; Geysen in published European Patent Application 0 138 855 and Pimmg in U.S. Pat. No. 5,143,854. Such SCLs provide the efficient synthesis of an extraordinary number of various peptides in such libraries and the rapid screening of the library that identifies lead pharmaceutical peptides.
Peptides have been, and remain, attractive targets for drug discovery. Their high affinities and specificities toward biological receptors as well as the ease with which large peptide libraries can be combinatorially synthesized make them attractive drug targets. The screening of peptide libraries has led to the identification of many biologically-active lead compounds. However, the therapeutic application of peptides is limited by their poor stability and bioavailability in vivo. Therefore, there is a need to synthesize and screen compounds that can maintain high affinity and specificity toward biological receptors, while exhibiting improved pharmacological properties relative to peptides.
Combinatorial approaches have recently been extended to xe2x80x9corganicxe2x80x9d or non-peptide libraries.
Significantly, many biologically active compounds contain the imidazole moiety. Such compounds are conformationally constrained scaffolds, are quite common in nature and many imidazole-containing natural products have been isolated encompassing a wide range of biological activities. The imidazole ring system is of particular importance because it is present in the essential amino acid histidine. The histidine residues are found at the active site of ribonuclease and several other enzymes. Drugs such as cimetidine were designed with histamine itself as the starting point [C. R. Ganellin, in Medicinal Chemistry, ed. S. M. Roberts and B. J. Price, Academic Press, London, 1985, p. 93; G. J. Durant, Chem Soc. Rev., 1985, 84, 375].
Several other classes of drugs are based on the imidazole ring. 2-Nitroimidazole (azomycin) is a naturally occurring antibiotic and some synthetic nitroimidazoles are active against intestinal infections (Reviews: Nitroimidazoles; Chemistry; Pharmacology and Clinical Applications, eds. A. Breccia, B. Cavalleri, and G. E. Adams, Plenum Press, New York, 1982; J. H. Boyer, Nitrazoles, VCH, Deerfield Beach, Fla., 1986).
Imidazole-containing moieties are found in many biologically active compounds and are known to have useful therapeutic implications. There is a need to further study and develop large numbers of [3,5,7]-1H-imidazo[1,5-a]imidazol-2(3H)-one compounds and their binding to biological receptors. These compounds of the present invention are principally derived from the synthesis of dipeptides, but the dipeptides are substantially modified. In short, they are chemically modified through, acylation and cyclization via Bischler-Naprielski reaction into the subject [3,5,7]-1H-imidazo[1,5-a]imidazol-2(3H)-one, thus providing mixtures and individual compounds of substantial diversity.
The invention provides a rapid approach for combinatorial synthesis and screening of individual compounds and libraries of [3,5,7]-1H-imidazo[1,5-a]imidazol-2(3H)-one compounds. The present invention further provides libraries and individual compounds and their pharmaceutically-acceptable salts of Formula I. The present invention also relates to the preparation of synthetic combinatorial libraries of organic compounds and their pharmaceutically-acceptable salts of Formula I, wherein R1, R2 and R3 have the meanings provided below. 
The present invention has several benefits and advantages. One benefit is the provision of a new synthesis for bicyclic [3,5,7]-1H-imidazo[1,5-a]imidazol-2(3H)-one compounds. The present invention provides a large array of diverse [3,5,7]-1H-imidazo[1,5-a]imidazol-2(3H)-one compounds that can be screened for biological activity, and as described below, are biologically active.
An advantage of the invention is that individual compounds can be prepared or libraries containing a plurality of compounds can be prepared.
Another benefit of the invention is that the yield of bicyclic compound produced is relatively great compared to that obtained in prior syntheses of the parental compound.
Still further benefits and advantages of the invention will be apparent to the skilled worker from the discussion that follows.
The present invention relates to the preparation and use of synthetic combinatorial libraries and individual compounds of a [3,5,7]-1H-imidazo[1,5-a]imidazol-2(3H)-one also referred to as a imidazo-imidizol-one that correspond in structure to Formula I, and their pharmaceutically-acceptable salts: 
wherein:
R1 and R2 are independently selected from the group consisting of a hydrogen atom (hydrido), C1-C10 alkyl, C1-C10 substituted alkyl, C7-C16 phenylalkyl, C7-C16 substituted phenylalkyl, phenyl, substituted phenyl, C3-C7 cycloalkyl, and a C3-C7 substituted cycloalkyl group.
R3 is selected from the group consisting of a hydrido, C1-C10 alkyl, C1-C10 substituted alkyl, C2-C10 alkenyl, C2-C10 substituted alkenyl, C2-C10 alkynyl, C2-C10 substituted alkynyl, C3-C7 substituted cycloalkyl, phenyl, C7-C16 phenylalkyl, C7-C16 phenylalkenyl, C7-C6 phenylalkenyl and a C7-C16 substituted phenylalkenyl group.
In one embodiment of the above bicyclic imidazo-imidizol-one of Formula I, wherein
R1 and R2 are independently selected from the group consisting of a hydrido, methyl, benzyl, 2-butyl, aminobutyl, N,N-dimethylaminobutyl, N-methylaminobutyl, N-methyl-N-benzylaminobutyl, 2-methylpropyl, methylsulfinylethyl, methylthioethyl, N,N-dimethylaminoethyl, N,N-dimethyl-aminopropyl, Nxe2x80x2,Nxe2x80x2,Nxe2x80x2-trimethylguanidinopropyl, Nxe2x80x2,Nxe2x80x2,Nxe2x80x2-tribenzylguanidinopropyl, Nxe2x80x2,Nxe2x80x2-dibenzylguanidinopropyl, Nxe2x80x2-methylguanidinopropyl, hydroxymethyl, 1-hydroxyethyl, 2-propyl, N-methyl-3-indolylmethyl, 4-methoxybenzyl, 4-hydroxybenzyl, propyl, butyl, cyclohexylmethyl, phenyl, 2-naphthylmethyl, and a 4-imidazolylmethyl substituent; and
R3 is selected from the group consisting of a 1-phenyl-1-cyclopropyl, 1-phenylbutyl, 2-phenylbutyl, 3-fluorobenzyl, 3-bromobenzyl, xcex1,xcex1,xcex1-trifluoro-m-xylyl, p-xylyl, 4-fluorobenzyl, 3-methoxybenzyl, 4-bromobenzyl, 4-methoxybenzyl, 4-ethoxybenzyl, 4-isobutyl-a-methyl-benzyl, 3,4-dichlorobenzyl, 3,5-bis-(trifluoromethyl)-benzyl, 2-(3,4-dimethoxyphenyl)-ethyl, 4-biphenylmethyl, xcex2-methyl-styryl, 2-(trifluoromethyl)-styryl, 3,4-dimethoxybenzyl, 3,4-dihydroxybenzyl, 2-methoxystyryl, 3,4-dihydroxystyryl, 2-hydroxystyryl, phenyl, 4-chlorostyryl, 3-methoxyphenyl, 4-isopropylphenyl, 4-vinylphenyl, 4-fluorophenyl, 4-bromophenyl, 3,4-dimethoxystyryl, 4-hydroxyphenyl, trans-styryl, 3,4-dimethylphenyl, 3-fluoro-4-methylphenyl, 3-bromo-4-methyl-phenyl, 3-iodo-4-methyl-phenyl, 3,4-dichlorophenyl, 4-biphenyl, 3,4-difluorophenyl, m-tolyl, benzyl, phenethyl, 3-methoxy-4-methylphenyl, 3-phenylpropyl, 4-butylphenyl, 3,5-dimethylphenyl, 3,5-bis-(trifluoromethyl)-phenyl, 3,4-dimethoxyphenyl, 4-ethyl-4-biphenyl, 3,4,5-triethoxyphenyl, propyl, hexyl, isopropyl, 2-butyl, isobutyl, 2-pentyl, isovaleryl, 3-heptyl, 1-propenyl, 2-propenyl, trans-2-pentenyl, 1-ethyl-1-pentenyl, p-tolyl, p-anisyl, t-butyl, neopentyl, cyclohexyl, cyclohexylmethyl, dicyclohexylmethyl, cyclohexylpropyl, cycloheptyl, methyl, 2-methylcyclopropyl, cyclobutyl, cyclopentyl, cyclopentylethyl, 2-furyl, cyclohexylethyl, 4-methylcyclohexyl, 4-tert-butyl-cyclohexyl, 1-adamantyl, 4-methylcyclohexylmethyl, 1,3-pentadienyl, 2-buten-2-yl, 2-norbornanemethyl, 1-adamantanemethyl, and a 3-pentyl, 2-thiophene substituent.
In one of the preferred embodiments of the present invention, the R groups are those as immediately defined above.
In the above Formula the stereochemistry of the chiral R1 group can independently be in the R or S configuration, or a mixture of the two. For instance, as will be described in further detail below, the R1 group can be the side chain substituent of the xcex1-carbon of various amino acids. The amino acids can be in the L- or D-configuration, resulting in the same R group varying only in its stereochemistry. As a consequence of an R1 substituent being in one or both or two stereoconfigurations, the R1 group is usually illustrated bonded to the bicyclic ring by a wavy line.
It is also noted that a compound of Formula I can exist in two tautomeric forms; i.e., in the keto or enol forms. Those two tautomeric forms are illustrated in Formula IA, below. 
For convenience, a contemplated compound of Formula I (IA) is usually depicted and discussed as being in the keto form (imidazo-imidizol-one) with the understanding that both keto and enol forms are present in equilibrium.
Formulas of the two tautomers in both stereoconfigurations are shown below. 
In any of the Formulas herein, the term xe2x80x9cC1-C10 alkylxe2x80x9d denotes a straight or branched chain radical such as a methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, amyl, tert-amyl, hexyl, heptyl, decyl group and the like. The term xe2x80x9clower alkylxe2x80x9d denotes a C1-C4 alkyl group. A preferred xe2x80x9cC1-C10 alkylxe2x80x9d group is a methyl group.
The term xe2x80x9cC2-C10 alkenylxe2x80x9d denotes a radical such as a vinyl, allyl, 2-butenyl, 3-butenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, 5-hexenyl, 2-heptenyl, 3-heptenyl, 4-heptenyl, 5-heptenyl, 6-heptenyl and a 2-decenyl group and the like, as well as dienes and trienes of straight and branched chains containing up to ten carbon atoms and at least one carbon-to-carbon (ethylenic) double bond.
The term xe2x80x9cC2-C10 alkynylxe2x80x9d denotes a radical such as ethynyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl, decynyl and the like, as well as di- and triynes of straight and branched chains containing up to ten carbon atoms and at least one carbon-to-carbon (acetylenic) triple bond.
The term xe2x80x9cC2-C10 substituted alkylxe2x80x9d, xe2x80x9cC2-C10 substituted alkenylxe2x80x9d and xe2x80x9cC2-C10 substituted alkenylxe2x80x9d denote that the above C1-C10 alkyl group and C2-C10 alkenyl and alkynyl groups are substituted by one or more, and preferably one or two, halogen, hydroxy, protected hydroxy, C3-C7 cycloalkyl, C3-C7 substituted cycloalkyl, naphthyl, substituted naphthyl, adamantyl, abietyl, thiofuranyl, indolyl, substituted indolyl, amino, protected amino, (monosubstituted) amino, protected (monosubstituted) amino, (disubstituted) amino, guanidino, (monosubstituted) guanidino, (disubstituted) guanidino, (trisubstituted) guanidino, imidazolyl pyrolidinyl, C1-C7 acyloxy, nitro, heterocycle, substituted heterocycle, C1-C4 alkyl ester, carboxy, protected carboxy, carbamoyl, carbamoyloxy, carboxamide, protected carboxamide, cyano, methylsulfonylamino, methylsulfonyl, sulfhydryl, C1-C4 alkylthio, C1-C4 alkyl sulfonyl or C1-C4 alkoxy groups. The substituted alkyl groups can be substituted once or more, and preferably once or twice, with the same or with different substituents.
Examples of the above substituted alkyl groups include the cyanomethyl, nitromethyl, chloromethyl, hydroxymethyl, tetrahydro-pyranyloxymethyl, trityloxymethyl, propionyloxymethyl, aminomethyl, carboxymethyl, allyloxycarbonylmethyl, allylcarbonyl-aminomethyl, carbamoyloxymethyl, methoxymethyl, ethoxymethyl, t-butoxymethyl, acetoxymethyl, chloromethyl, bromomethyl, iodomethyl, 6-hydroxy-hexyl, 2,4-dichloro(n-butyl), 2-amino(isopropyl), 2-carbamoyloxyethyl chloroethyl, bromoethyl, fluoroethyl, iodoethyl, chloropropyl, bromopropyl, fluoropropyl, iodopropyl and the like.
In preferred embodiments of the subject invention, C1-C1 alkyl, C2-C10 alkenyl, C2-C10 alkynyl, C1-C10 substituted alkyl, C2-C10 substituted alkenyl, or C2-C10 substituted alkynyl, are more preferably C1-C7 or C2-C7, respectively, and more preferably, C1-C6 or C2-C6 as is appropriate for unsaturated substituents. However, it should be appreciated by those of skill in the art that one or a few carbons usually can be added to an alkyl, alkenyl, alkynyl, substituted or unsubstituted, without substantially modifying the structure and function of the subject compounds and that, therefore, such additions would not depart from the spirit of the invention.
The term xe2x80x9cC1-C4 alkoxyxe2x80x9d as used herein denotes groups that are ether groups containing up to four carbon atoms such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, t-butoxy and like groups. A preferred C1-C4 alkoxy group is methoxy.
The term xe2x80x9cC1-C7 acyloxyxe2x80x9d denotes a carboxy group-containing substituent containing up seven carbon atoms such as formyloxy, acetoxy, propanoyloxy, butanoyloxy, pentanoyloxy, hexanoyloxy, heptanoyloxy, benzoyloxy and the like.
Similarly, the term xe2x80x9cC1-C7 acylxe2x80x9d encompasses groups such as formyl, acetyl, propionoyl, butyroyl, pentanoyl, hexanoyl, heptanoyl, benzoyl and the like.
The substituent term xe2x80x9cC3-C7 cycloalkylxe2x80x9d includes the cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or cycloheptyl rings. The substituent term xe2x80x9cC3-C7 substituted cycloalkylxe2x80x9d indicates an above cycloalkyl ring substituted by a halogen, hydroxy, protected hydroxy, phenyl, substituted phenyl, heterocycle, substituted heterocycle, C1-C10 alkyl, C1-C4 alkoxy, carboxy, protected carboxy, amino, or protected amino.
The substituent term xe2x80x9cC5-C7 cycloalkenylxe2x80x9d indicates a substituent that is itself a 1-, 2-, or 3-substituted cyclopentenyl ring, a 1-, 2-, 3- or 4-substituted cyclohexenyl ring or a 1-, 2-, 3-,4- or 5-substituted cycloheptenyl ring, whereas the term xe2x80x9csubstituted C3-C7 cycloalkenylxe2x80x9d denotes the above C3-C7 cycloalkenyl rings substituted by a C1-C10 alkyl radical, halogen, hydroxy, protected hydroxy, C1-C4 alkoxy, carboxy, protected carboxy, amino, or protected amino.
The term xe2x80x9cheterocyclic ringxe2x80x9d or xe2x80x9cheterocyclexe2x80x9d denotes an optionally substituted 5-membered or 6-membered ring that has 1 to 4 heteroatoms, such as oxygen, sulfur and/or nitrogen, in particular nitrogen either alone or in conjunction with sulfur or oxygen ring atoms. These five-membered or six-membered rings can be fully unsaturated or partially unsaturated, with fully unsaturated rings being preferred.
Preferred heterocyclic rings include pyridino, pyrimidino, and pyrazino, furano, and thiofurano rings. The heterocyles can be substituted or unsubstituted as for example, with such substituents as those described in relation to substituted phenyl or substituted naphthyl.
The term xe2x80x9cC7-C16 phenylalkylxe2x80x9d or xe2x80x9cC7-C16 aralkylxe2x80x9d denotes a C1-C10 alkyl group substituted at any position by a phenyl ring. Examples of such a group include benzyl, 2-phenylethyl, 3-phenyl(n-prop-1-yl), 4-phenyl(hex-1-yl), 3-phenyl(n-am-2-yl), 3-phenyl(sec-butyl), and the like. A preferred C7-C16 phenylalkyl group is the benzyl group.
The term xe2x80x9cC7-C16 substituted phenylalkylxe2x80x9d denotes an above C7-C16 phenylalkyl group substituted on the C1-C10 alkyl portion with one or more, and preferably one or two, groups selected from the group consisting of a halogen, hydroxy, protected hydroxy, keto, C2-C3 cyclic ketal phenyl, amino, protected amino, C1-C7 acyloxy, nitro, carboxy, protected carboxy, carbamoyl, carbamoyloxy, cyano, N-(methyl-sulfonylamino) or C1-C4 alkoxy group, whose phenyl group portion can be substituted with 1 or 2 groups selected from the group consisting of a halogen, hydroxy, protected hydroxy, nitro, C1-C10 alkyl, C1-C6 substituted alkyl, C1-C4 alkoxy, carboxy, protected carboxy, carboxymethyl, protected carboxymethyl, hydroxymethyl, protected hydroxymethyl, aminomethyl, protected aminomethyl, amino, (monosubstituted) amino, (disubstituted) amino, a N-(methylsulfonylamino) group, or a phenyl group that is itself substituted or unsubstituted. When either the C1-C10 alkyl portion or the phenyl portion or both are mono- or di-substituted, the substituents can be the same or different.
Examples of xe2x80x9cC7-C16 substituted phenylalkylxe2x80x9d include groups such as 2-phenyl-1-chloroethyl, 2-(4-methoxyphenyl)eth-1-yl, 2,6-dihydroxy-4-phenyl(n-hex-2-yl), 5-cyano-3-methoxy-2-phenyl(n-pent-3-yl), 3-(2,6-dimethylphenyl)n-prop-1-yl, 4-chloro-3-aminobenzyl, 6-(4-methoxyphenyl)-3-carboxy(n-hex-1-yl), 5-(4-aminomethyl-phenyl)-3-(aminomethyl)(n-pent-2-yl), 5-phenyl-3-keto-(n-pent-1-yl), 4-(4-aminophenyl)-4-(I.4-oxetanyl)(n-but-1-yl), and the like.
The term xe2x80x9cC7-C16 phenylalkenylxe2x80x9d denotes a C1-C10 alkenyl group substituted at any position by a phenyl ring. The term xe2x80x9cC7-C16 substituted phenylalkenylxe2x80x9d denotes a C7-C16 arylalkenyl group substituted on the C1-C10 alkenyl portion. Substituents can the same as those as defined above in relation to C7-C16 phenylalkyl and C7-C16 substituted phenylalkyl. A preferred C7-C16 substituted phenylalkenyl is 3-(4-nitrophenyl)-2-propenyl.
The term xe2x80x9csubstituted phenylxe2x80x9d specifies a phenyl group substituted at one or more positions, preferably at one or two positions, with moieties selected from the group consisting of halogen, hydroxy, protected hydroxy, cyano, nitro, C1-C10 alkyl, C1-C10 substituted alkyl, C1-C4 alkoxy, carboxy, protected carboxy, carboxymethyl, protected carboxymethyl, hydroxymethyl, protected hydroxymethyl, amino, protected anilino, (monosubstituted)amino, protected (monosubstituted) amino, (disubstituted)amino, trifluoromethyl, N-(methylsulfonylamino), or phenyl that is itself substituted or unsubstituted such that, for example, a biphenyl group results.
Illustrative substituents embraced by the term xe2x80x9csubstituted phenyllxe2x80x9d include a mono- or di(halo)phenyl group such as 4-chlorophenyl, 2,6-dichlorophenyl, 2,5-dichlorophenyl, 3,4-dichlorophenyl, 3-chlorophenyl, 3-bromophenyl, 4-bromophenyl, 3,4-dibromophenyl, 3-chloro-4-fluorophenyl, 2-fluorophenyl and the like; a mono or di(hydroxy)phenyl groups such as 4-hydroxyphenyl, 3-hydroxyphenyl, 2,4-dihydroxyphenyl, the protected hydroxy derivatives thereof and the like; a nitrophenyl group such as 3- or 4-nitrophenyl, a cyanophenyl group for example, 4-cyanophenyl; a mono- or di(lower alkyl)phenyl group such as 4-methylphenyl, 2,4-dimethylphenyl, 2-methylphenyl, 4-(isopropyl)phenyl, 4-ethylphenyl, 3-(n-prop-1-yl)phenyl and the like: a mono or di(alkoxyl)phenyl group for example, 2,6-dimethoxyphenyl, 4-methoxyphenyl, 3-ethoxyphenyl, 4-(isopropoxy)phenyl, 4-(t-butoxy)phenyl, 3-ethoxy-4-methoxyphenyl, 3-(4-methylphenoxy)phenyl, and the like; 3- or 4-trifluoromethylphenyl; a mono- or dicarboxyphenyl or (protected carboxy)phenyl group such as 4-carboxyphenyl or 2,4-di(protected carboxy)phenyl; a mono-or di(hydroxymethyl)phenyl or (protected hydroxymethyl)phenyl such as 3-(protected hydroxymethyl)phenyl or 3,4-di(hydroxymethyl)phenyl; a mono- or di(aminomethyl) phenyl or (protected aminomethyl)phenyl such as 2-(aminomethyl)phenyl or 2,4-(protected aminomethyl) phenyl; or a mono- or di(N-(methylsulfonylamino))phenyl such as 3-(N-(methylsulfonylamino))phenyl. Also, the term xe2x80x9csubstituted phenylxe2x80x9d represents disubstituted phenyl groups wherein the substituents are different. For example, 3-methyl-4-hydroxyphenyl, 3-chloro-4-hydroxyphenyl, 2-methoxy-4-bromophenyl, 4-ethyl-2-hydroxyphenyl, 3-hydroxy-4-nitrophenyl, 2-hydroxy-4-chlorophenyl and the like are contemplated.
The term xe2x80x9csubstituted naphthylxe2x80x9d specifies a naphthyl group substituted with one or more, and preferably one or two moieties selected from the group consisting of a halogen, hydroxy, protected hydroxy, cyano, nitro, C1-C10 alkyl, C1-C4 alkoxy, carboxy, protected carboxy, carboxymethyl, protected carboxymethyl, hydroxymethyl, protected hydroxymethyl, amino, protected amino, (monosubstituted) amino, protected (monosubstituted)amino, (disubstituted) amino trifluoromethyl, or a N-(methylsulfonylamino) group. Examples of substituted naphthyl include 2-(methoxy)naphthyl and 4-(methoxy)naphthyl.
The term xe2x80x9csubstituted indolylxe2x80x9d specifies a indolyl group substituted, either at the nitrogen or carbon, or both, with one or more, and preferably one or two, moieties selected from the group consisting of a halogen, hydroxy, protected hydroxy, cyano, nitro, C1-C10 alkyl, C1-C10 substituted alkyl, C1-C10 alkenyl, C7-C16 phenylalkyl, C7-C16 substituted phenylalkyl, C1-C6 alkoxy, carboxy, protected carboxy, carboxymethyl, protected carboxymethyl, hydroxymethyl, protected hydroxymethyl, amino, protected amino, monosubstituted amino, or a disubstituted amino group.
Examples of the term xe2x80x9csubstituted indolylxe2x80x9d includes such groups as 6-fluoro, 5-fluoro, 5-bromo, 5-hydroxy, 5-methyl, 6-methyl, 7-methyl, 1-methyl, 1-ethyl, 1-benzyl, 1-napthylmethyl, and the like. An example of a disubstituted indolyl is 1-methyl-5-methyl indolyl.
The terms xe2x80x9chaloxe2x80x9d and xe2x80x9chalogenxe2x80x9d refer to the fluoro, chloro, bromo, or iodo groups.
The term xe2x80x9c(monosubstituted)aminoxe2x80x9d refers to an amino group with one substituent selected from the group consisting of phenyl, substituted phenyl, C1-C10 alkyl, and C7-C16 arylalkyl, wherein the latter three substituent terms are as defined above. The (monosubstituted)amino can additionally have an amino-protecting group as encompassed by the term xe2x80x9cprotected (monosubstituted)amino.xe2x80x9d
The term xe2x80x9c(disubstituted)aminoxe2x80x9d refers to amino groups with two substituents selected from the group consisting of phenyl, substituted phenyl, C1-C10 alkyl, and C7-C16 arylalkyl wherein the latter three substituent terms are as described above. The two substituents can be the same or different.
The terms xe2x80x9c(monosubstituted)guanidinoxe2x80x9d, xe2x80x9c(disubstituted)guanidino.xe2x80x9d and xe2x80x9c(trisubstituted)-guanidinoxe2x80x9d are used to mean that a guanidino group is substituted with one, two, or three substituents, respectively. The substituents can be any of those as defined above in relation to (monosubstituted)-amino and (disubstituted)amino and, where more than one substituent is present, the substituents can be the same or different.
The terms xe2x80x9c(monosubstituted) imidizol-one imidazole, xe2x80x9c(disubstituted) imidizol-one imidazole.xe2x80x9d and xe2x80x9c(trisubstituted) imidizol-one imidazolexe2x80x9d mean compounds in which the imidizol-one imidazole group is substituted with one, two, or three substituents, respectively. The substituents can be any of those as defined above in relation to a (monosubstituted)-amino or (disubstituted)amino group and where more than one substituent is present. The substituents can be the same or different.
The term xe2x80x9camino-protecting groupxe2x80x9d as used herein refers to one or more selectively removable substituents on the amino group commonly employed to block or protect the amino functionality. The term xe2x80x9cprotected (monosubstituted)aminoxe2x80x9d means there is an amino-protecting group on the monosubstituted amino nitrogen atom. In addition, the term xe2x80x9cprotected carboxamidexe2x80x9d means there is an amino-protecting group present replacing the proton of the amido nitrogen so that di-N-alkylation.
Examples of such amino-protecting groups include the formyl (xe2x80x9cForxe2x80x9d) group, the trityl group (Trt), the phthalimido group, the trichloroacetyl group, the chloroacetyl, bromoacetyl, and iodoacetyl groups. Urethane blocking groups, such as t-butoxy-carbonyl (xe2x80x9cBocxe2x80x9d), 2-(4-biphenylyl)propyl(2)-oxycarbonyl (xe2x80x9cBpocxe2x80x9d), 2-phenylpropyl(2)oxycarbonyl (xe2x80x9cPocxe2x80x9d), 2-(4-xenyl)-isopropoxycarbonyl, 1,1-diphenylethyl(1)oxycarbonyl, 1,1-diphenylpropyl(1)oxycarbonyl, 2-(3,5-dimethoxyphenyl) propyl(2)oxycarbonyl (xe2x80x9cDdzxe2x80x9d), 2-(p-5-toluyl)propyl-(2) oxycarbonyl, cyclo-pentanyloxycarbonyl, 1-methylcyclopentanyl-oxycarbonyl, cyclohexanyloxycarbonyl, 1-methyl-cyclohexanyloxycarbonyl, 2-methylcyclohexanyloxycarbonyl, 2-(4-toluylsulfonyl)ethoxycarbonyl, 2-(methylsulfonyl)ethoxycarbonyl, 2-(triphenylphosphino)ethoxycarbonyl, 9-fluoroenylmethoxycarbonyl (xe2x80x9cFmocxe2x80x9d), 2-(trimethylsilyl)ethoxycarbonyl, allyloxycarbonyl, 1-(trimethylsilylmethyl)prop-1-enyloxycarbonyl, 5-benz-isoxalylmethoxycarbonyl, 4-acetoxybenzyloxycarbonyl, 2,2,2-trichloroethoxycarbonyl, 2-ethynyl(2)propoxycarbonyl, cyclopropylmethoxycarbonyl, isobornyloxycarbonyl, 1-piperidyloxycarbonyl, benzyloxycarbonyl (xe2x80x9cZxe2x80x9d), 4-phenylbenzyloxycarbonyl, 2-methylbenzyloxycarbonyl, xcex1-2,4,5,-tetramethylbenzyloxycarbonyl (xe2x80x9cTmzxe2x80x9d), 4-methoxybenzyl-oxycarbonyl, 4-fluorobenzyloxycarbonyl, 4-chloro-benzyloxycarbonyl, 3-chlorobenzyloxycarbonyl, 2-chlorobenzyloxycarbonyl, dichlorobenzyloxycarbonyl, 4-bromobenzyloxycarbonyl, 3-bromobenzyloxycarbonyl, 4-nitrobenzyloxycarbonyl, 4-cyanobenzyIioxycarbonyl, 4-(decyloxy)benzyloxycarbonyl, and the like, the benzoylmethylsulfonyl group, dithiasuccinoyl (xe2x80x9cDtsxe2x80x99) group, the 2-(nitro)phenylsulfenyl group (xe2x80x9cNpsxe2x80x99), the diphenylphosphine oxide group, and like amino-protecting groups. The species of amino-protecting group employed is usually not critical so long as the derivatized amino group is stable to the conditions of the subsequent reactions and can be removed at the appropriate point without disrupting the remainder of the compound. Preferred amino-protecting groups are Boc and Fmoc.
Further examples of amino-protecting groups embraced to by the above term are well known in organic synthesis and the peptide art and are described by, for example T. W. Greene and P. G. M. Wuts, Protective Groups in Organic Synthesis, 2nd ed., John Wiley and Sons. New York., Chapter 7, 1991; M. Bodanzsky, Principles of Peptide Synthesis, 1st and 2nd revised eds., Springer-Verlag, New York, 1984 and 1993; and Stewart and Young, Solid Phase Peptide Synthesis, 2nd ed., Pierce Chemical Co, Rockford. IL 1984.
The related term xe2x80x9cprotected aminoxe2x80x9d defines an amino group substituted with an amino-protecting group discussed above.
The term xe2x80x9ccarboxy-protecting groupxe2x80x9d as used herein refers to one of the ester derivatives of the carboxylic acid group commonly employed to block or protect the carboxylic acid group while reactions are carried out on other functional groups on the compound. Examples of such carboxylic acid protecting groups include 4-nitrobenzyl, 4-methoxybenzyl, 3,4-dimethoxybenzyl, 2,4-dimethoxybenzyl, 2,4,6-trimethoxybenzyl, 2,4,6-trimethylbenzyl, pentamethylbenzyl, 3,4-methylene-dioxybenzyl, benzhydryl, 4,4xe2x80x2-methoxytrityl, 4,4xe2x80x2,4xe2x80x3-trimethoxytrityl, 2-phenylprop-2-yl, trimethylsilyl, t-butyldimethylsilyl, 2,2,2-trichloroethyl, xcex2-(trimethylsilyl)ethyl, xcex2-[di(n-butyl)methylsilyl]ethyl, p-toluenesulfonylethyl, 4-nitrobenzyl-sulfonylethyl, allyl, cinnamyl, 1-(trimethylsilylmethyl)-prop-1-en-3-yl, and like moieties. The species of carboxy-protecting group employed is also usually not critical so long as the derivatized carboxylic acid is stable to the conditions of subsequent reactions and can be removed at the appropriate point without disrupting the remainder of the molecule.
Further examples of these groups are found in E. Haslam, Protective Groups in Organic Chemistry, J. G. W. McOmie Ed., Plenum Press, New York 1973, Chapter 5 and T. W. Greene and P. G. M. Wuts, Protective Groups in Organic Synthesis 2nd ed., John Wiley and Sons, New York, 1991, Chapter 5, each of which is incorporated herein by reference. A related term is xe2x80x9cprotected-carboxyxe2x80x9d, which refers to a carboxy group substituted with one of the above carboxy-protecting groups.
The term xe2x80x9chydroxy-protecting groupxe2x80x9d refers to readily cleavable groups bonded to hydroxyl groups, such as the tetrahydropyranyl, 2-methoxyprop-2-yl, 1-ethoxyeth-1-yl, methoxymethyl, xcex2-methoxyethoxymethyl, methylthiomethyl, t-butyl, t-amyl, trityl, 4-methoxytrityl, 4,4xe2x80x2-dimethoxytrityl, 4,4xe2x80x2,4xe2x80x3-trimethoxytrityl, benzyl, allyl, trimethylsilyl, (t-butyl)dimethylsilyl and 2,2,2-trichloroethoxycarbonyl groups, and the like. The species of hydroxy-protecting groups is also usually not critical so long as the derivatized hydroxyl group is stable to the conditions of subsequent reaction(s) and can be removed at the appropriate point without disrupting the remainder of the compound.
Further examples of hydroxy-protecting groups are described by C. B. Reese and E Haslam, Protective Groups in Organic Chemistry, J. G. W. McOmie, Ed., Plentun Press, New York 1973, Chapters 3 and 4, respectively, and T. W. Greene and P. G. M. Wuts, Protective Groups in Organic Synthesis, 2nd ed., John Wiley and Sons, New York, 1991, Chapters 2 and 3, whose disclosures are also incorporated by reference.
The substituent term xe2x80x9cC1-C4 alkylthioxe2x80x9d refers to sulfide groups such as methylthio, ethylthio, n-propylthio, isopropylthio, xcex1-butylthio, t-butylthio and like groups.
The substituent term xe2x80x9cC1-C4 alkylsulfoxidexe2x80x9d indicates sulfoxide groups such as methylsulfoxide, ethylsulfoxide, xcex1-propylsulfoxide, iso-propyl-sulfoxide, n-butylsulfoxide, sec-butylsulfoxide, and the like.
The term xe2x80x9cC1-C4 alkylsulfonylxe2x80x9d encompasses groups such as methylsulfonyl, ethylsulfonyl, n-propylsulfonyl, isopropylsulfonyl, a-butylsulfonyl, t-butylsulfonyl, and the like.
Phenylthio, phenyl sulfoxide, and phenylsulfonyl compounds are known in the art and these have their art-recognized definitions. By xe2x80x9csubstituted phenylthioxe2x80x9d, xe2x80x9csubstituted phenyl sulfoxidexe2x80x9d, and xe2x80x9csubstituted phenylsulfonylxe2x80x9d, is meant that the phenyl can be substituted as described above in relation to xe2x80x9csubstituted phenyl.xe2x80x9d
The substituent terms xe2x80x9ccyclic C2-C10 alkylenexe2x80x9d, xe2x80x9csubstituted cyclic C2-C10 alkylenexe2x80x9d, xe2x80x9ccyclic C2-C10 heteroalkylene.xe2x80x9d and xe2x80x9csubstituted cyclic C2-C10 heteroakylenexe2x80x9d defines a cyclic group bonded (xe2x80x9cfusedxe2x80x9d) to the phenyl radical. The cyclic group can be saturated or contain one or two double bonds. Furthermore, the cyclic group can have one or two methylene groups replaced by one or two oxygen, nitrogen or sulfur atoms.
The cyclic alkylene or heteroalkylene group can be substituted once or twice by substituents selected from the group consisting of hydroxy, protected-hydroxy, carboxy, protected-carboxy, keto, ketal, C1-C4 alkoxycarbonyl, C1-C4 alkanoyl, C1-C10 alkyl, carbamoyl, C1-C4 alkoxy, C1-C4, alkylthio, C1-C4 alkylsulfoxide, C1-C4 alkylsulfonyl, halo, amino, protected-amino, hydroxymethyl and a protected-hydroxymethyl group.
A cyclic alkylene or heteroalkylene group fused onto the benzene radical can contain two to ten ring members, but it preferably contains four to six members. Examples of such saturated cyclic groups include a bicyclic ring system that is a 2,3-dihydroindanyl or a tetralin ring. When the cyclic groups are unsaturated, examples occur when the resultant bicyclic ring system is a naphthyl ring or indanyl.
An example of a cyclic group that can be fused to a phenyl radical that has two oxygen atoms and that is fully saturated is dioxanyl. Examples of fused cyclic groups that each contain one oxygen atom and one or two double bonds occur when the phenyl ring is fused to a furyl, pyranyl, dihydrofuryl or dihydropyranyl ring. Cyclic groups that each have one nitrogen atom and contain one or two double more double bonds are illustrated where the phenyl is fused to a pyridino or pyrano ring. An example of a fused ring system having one nitrogen and two phenyl radicals is a carbozyl group. Examples of cyclic groups that each have one sulfur atom and contain one or two double bonds occur where the benzene ring is fused to a thieno, thiopyrano, dihydrothieno, or dihydrothiopyrano ring. Examples of cyclic groups that contain two heteroatoms selected from sulfur and nitrogen and one or two double bonds occur where the phenyl ring is fused to a thiazolo, isothiazolo, dihydrothiazolo or dihydroisothiazolo ring. Examples of cyclic groups that contain two heteroatoms selected from oxygen and nitrogen and one or two double bonds occur where the benzene ring is fused to an oxazole, isoxazole, dihydroxazole or dihydroisoxazole ring. Examples of cyclic groups that contain two nitrogen heteroatoms and one or two double bonds occur where the benzene ring is fused to a pyrazolo, imidazolo, dihydropyrazolo or dihydroimidazolo ring.
Examples of cyclic groups that each have one nitrogen atom and contain one or two double more double bonds occur when the phenyl is fused to a pyridino or pyrano ring. An example of a fused ring system having one nitrogen and two phenyl radicals is a carbozyl group. Examples of cyclic groups that each have one sulfur atom and contain one or two double bonds occur when the phenyl is fused to a thieno, thiopyrano, dihydrothieno, or dihydrothiopyrano ring.
Examples of cyclic groups that contain two heteroatoms selected from sulfur and nitrogen and one or two double bonds occur when the phenyl ring is fused to a thiazolo, isothiazolo, dihydrothiazolo or dihydroisothiazolo ring. Examples of cyclic groups that contain two heteroatoms selected from oxygen and nitrogen and one or two double bonds occur when the benzene ring, is fused to an oxazolo, isoxazolo, dihydroox-azolo or dihydroisoxazolo ring. Examples of cyclic groups which contain two nitrogen heteroatoms and one or two double bonds occur when the benzene ring is fused to a pyrazolo, Imidazolo, dihydropyrazolo or dihydroimidazolo ring.
Pharmaceutical Compositions
A pharmaceutical composition for treating infections, pain, or other indications treatable by a contemplated imidazo-imidazol-one is administered to a subject in need of the medication at dosage levels of about 0.7 to about 7000 mg per day, and preferably about 1 to about 500 mg per day, for a normal human adult of approximately 70 kg of body weight. This broadly translates into a dosage of about 0.01 to about 100 mg/kg of body weight per day of an imidizo-imidazol-one compound of Formula I as active ingredient. The specific dosages employed, however, can be varied depending upon the requirements of the patient, the severity of the condition being treated, and the activity of the compound being employed. The determination of optimum dosages for a particular situation is within the skill of the art.
One or more of the imidizo-imidazol-one compounds of Formula I can be present as a pharmaceutically-acceptable salt. The term xe2x80x9cpharmaceutically-acceptable saltxe2x80x9d encompasses those salts that form with the carboxylate anions or ammonium cations and include salts formed with the organic and inorganic cations and anions discussed below. Furthermore, the term includes salts that form by standard acid-base reactions with basic groups (such as amino groups) and organic or inorganic acids. Such acids include hydrochloric, sulfuric, phosphoric, acetic, succinic, citric lactic, maleic, fumaric, palmitic, cholic, pamoic, mucic, D-glutamic, d-camphoric, glutaric, phthalic, tartaric, lauricc, stearic, salicyclic, methanesulfonic, benzenesulfonic, sorbic, picric, benzoic, cinnamic, and like acids.
The term xe2x80x9corganic or inorganic cationxe2x80x9d refers to counterions for the carboxylate anion of a carboxylate salt. The counter-ions are chosen from the alkali and alkaline earth metals, (such as lithium, sodium, potassium, barium and calcium): ammonium; and the organic cations such as (dibenzylammonium, benzylammonium, 2-hydroxymethylammonium, bis(2-hydroxyethyl)ammonium, phenylethylbenzyl ammonium, dibebenzylethylenediammoniurn, and like cations). Other cations encompassed by the above term include the protonated form of procaine, quinine and N-methylglucosamine, and the protonated forms of basic amino acids such as glycine, ornithine, histidine, phenylglycine, lysine and arginine. Furthermore, any zwitterionic form of the instant compounds formed by a carboxylic acid and an amino group is referred to by this term. A preferred cation for the carboxylate anion is the sodium cation.
A compound of Formula I can also be present as a solvate and hydrate. Thus, these compounds can crystallize with, for example, waters of hydration, or one, a number of, or any fraction thereof of molecules of the mother liquor solvent. The solvates and hydrates of such compounds are included within the scope of this invention.
One or more of the contemplated compounds can be in the biologically active ester form, such as the non-toxic, metabolically-labile ester-form. Such ester forms induce increased blood levels and prolong the efficacy of the corresponding non-esterified forms of the compounds. Ester groups that can be used include the lower alkoxymethyl groups (C1-C4 alkoxymethyl) for example, methoxymethyl, ethoxymethyl, isopropoxymethyl and the like; the xe2x80x94(C1-C4) alkoxyethyl groups, for example methoxyethyl, ethoxyethyl, propxyethyl, iso-propoxyethyl, and the like, the 2-oxo-1,3-dioxolen-4-ylmethyl groups such as 5-methyl-2-oxo-1,3-dioxolen-4-ylmethyl, 5-phenyl-2-oxo-1,3-dioxolen-4-ylmethyl, and the like, the C1-C3 alkylthiomethyl groups, for example methylthiomethyl, ethylthiomethyl, isopropylthiomethyl, and the like, the acyloxymethyl groups, for example pivaloyloxymethyl, pivaloyloxyethyl, a-acetoxymethyl, and the like, the ethoxycarbonyl-1-methyl group, the a-acetoxyethyl, the 3-phthalidyl or 5,6-dimethylphtalidyl groups, the 1-(C1-C4 alkyloxycarbonyloxy)ethyl groups such as the 1-(ethoxycarbonyloxy)ethyl group, and the 1-(C1-C4 alkylaminocarbonyloxy)ethyl groups such as the 1-methylaminocarbonyloxyethyl group.
For preparing pharmaceutical compositions containing compounds of the invention, inert, pharmaceutically acceptable carriers are used. The pharmaceutical carrier can be either solid or liquid. Solid form preparations include, for example, powders, tablets, dispersible granules, capsules, cachets, and suppositories.
A solid carrier can be one or more substances that can also act as diluents, flavoring agents, solubilizers, lubricants, suspending agents, binders, or tablet disintegrating agents; it can also be an encapsulating material.
In powders, the carrier is generally a finely divided solid that is in a mixture with the finely divided active component. In tablets, the active compound is mixed with the carrier having the necessary binding properties in suitable proportions and compacted in the shape and size desired.
For preparing pharmaceutical composition in the form of suppositories, a low-melting wax such as a mixture of fatty acid glycerides and cocoa butter is first melted and the active ingredient is dispersed therein by, for example, stirring. The molten homogeneous mixture is then poured into convenient-sized molds and allowed to cool and solidify.
Powders and tablets preferably contain between about 5% to about 70% by weight of the active ingredient. Suitable carriers include, for example, magnesium carbonate, magnesium stearate, talc, lactose, sugar, pectin, dextrin, starch, tragacanth, methyl cellulose, sodium carboxymethyl cellulose, a low-melting wax, cocoa butter and the like.
A pharmaceutical composition can include the formulation of the active compound with encapsulating material as a carrier providing a capsule in which the active component (with or without other carriers) is surrounded by a carrier, which is thus in association with it. In a similar manner, cachets are also included.
Tablets, powders, cachets, and capsules can be used as solid dosage forms suitable for oral administration.
Liquid pharmaceutical compositions include, for example, solutions suitable for oral or parenteral administration, or suspensions, and emulsions suitable for oral administration. Sterile water solutions of the active component or sterile solutions of the active component in solvents comprising water, ethanol, or propylene glycol are examples of liquid compositions suitable for parenteral administration.
Sterile solutions can be prepared by dissolving the active component in the desired solvent system, and then passing the resulting solution through a membrane filter to sterilize it or, alternatively, by dissolving the sterile compound in a previously sterilized solvent under sterile conditions.
Aqueous solutions for oral administration can be prepared by dissolving the active compound in water and adding suitable flavorants, coloring agents, stabilizers, and thickening agents as desired. Aqueous suspensions for oral use can be made by dispersing the finely divided active component in water together with a viscous material such as natural or synthetic gums, resins, methyl cellulose, sodium carboxymethyl cellulose, and other suspending agents known to the pharmaceutical formulation art.
Preferably, the pharmaceutical composition is in unit dosage form. In such form, the composition is divided into unit doses containing appropriate quantities of the active urea. The unit dosage form can be a packaged preparation, the package containing discrete quantities of the preparation, for example, packeted tablets, capsules, and powders in vials or ampules. The unit dosage form can also be a capsule, cachet, or tablet itself, or it can be the appropriate number of any of these packaged forms.
Library Synthesis and Use
As used herein, a chemical or combinatorial xe2x80x9d libraryxe2x80x9d is an intentionally created collection of a plurality of structurally similar, but different molecules. By xe2x80x9cstructurally similarxe2x80x9d, it is meant that the constituent compounds of a library have the same ring structure; i.e., a bicyclic imidizo-imidazol-one ring, and at least two positions at which substituents are bonded to the ring structure. It is preferred that the member compounds of the library also have the same substitution pattern of substituent groups; i.e., that the at least two substituents be bonded to the same ring positions in each member compound. The molecule members of the library are different in that each member has at least one different substituent group from the other members of the library. A library can contain two to thousands or millions of member compounds.
A particular library can also be comprised of members whose substituent groups are all different from each other. Thus, where the shared ring structure contains substituent groups at a plurality of positions, a library can be prepared in which the member molecules contain different groups at each position.
Alternatively, a plurality of sub-libraries or sets can also be prepared in which a first set has a first substituent that is held constant for all of the members (is present in all members) of the set, whereas the groups at the other substituent positions are different and constitute a mixture of groups at each substituent position. A second set of that plurality has a second, different, first substituent, and the same mixture of different groups at the other substituent positions. A third set of that plurality has a third, different first substituent, and the same mixture of different groups at the other substituent positions, and so on until one decides to stop making sets with different first substituents. Such set pluralities of structurally similar, but different compounds are also often referred to as libraries of libraries, and are particularly useful in ascertaining which compound or compounds of a library are active in an assay of choice.
A library can be prepared by the synthetic means discussed below or otherwise herein and screened for biological activity in a variety of formats (e.g. libraries of soluble molecules). Libraries of compounds can be attached to resin beads, silica chips or other solid supports). The libraries can be screened in any variety of assays, such as those detailed below as well as others useful for assessing the biological activity of imidazo-imidazol-ones. The libraries typically contain at least one active compound and are generally prepared such that the compounds are in equimolar quantities.
The nonsupport-bound library mixtures prepared herein were screened in solution in radio-receptor inhibition assays described in detail hereinafter. Deconvolution of highly active mixtures can then be carried out by iterative, or positional scanning methods. These techniques, the iterative approach or the positional scanning approach, can be utilized for finding other active compounds within the libraries of the present invention using any one of the below-described assays or others well known in the art.
The iterative approach is well-known and is set forth in general in Houghten et al., Nature, 354, 84-86 (1991) and Dooley et al., Science, 266, 2019-2022 (1994), both of which are incorporated herein by reference. In the iterative approach, for example, sub-libraries of a molecule having three variable groups are made wherein the first variable substituent is defined (known and held constant) within the sub-library. Each of the compounds with the defined variable group is reacted separately with each of the other possibilities at the second variable group position and the third variable position is a mixture of all of the possible substituents to form a plurality of sub-libraries whose first two substituent groups are known. These sub-libraries are each assayed to define the identity of the second variable in the sub-library having the highest activity in the screen of choice.
A new sub-library with the first two variable positions defined is separately reacted with each of the other possibilities at the remaining undefined variable position. As before, the identity of the third variable position in the sub-library having the highest activity is determined.
If more variables exist, this process is repeated for all variables, yielding the compound with each variable contributing to the highest desired activity in the screening process. Promising compounds from this process can then be synthesized on larger scale in traditional single-compound synthetic methods for further biological investigation.
The positional-scanning approach has been described for various libraries as described, for example, in R. Houghten et al. PCT/US91/08694 and U.S. Pat. No. 5,556,762, both of which are incorporated herein by reference. The positional scanning approach is used as described below in the preparation and screening of the libraries.
In the positional scanning approach, sub-libraries are made defining only one variable substituent with each set of sub-libraries and all possible sub-libraries with each single variable substituent defined (and all other possibilities at all of the other variable positions) is made and tested. From the instant description one skilled in the art can synthesize libraries wherein two fixed substituent positions are defined at a time. From the assaying of each single-variable defined library, the optimum substituent at that position is determined, pointing to the optimum or at least a series of compounds having a maximum of the desired biological activity. Thus, the number of sub-libraries for compounds with a single substituent position defined is the number of different substituents desired at that position, and the number of all the compounds in each sub-library is the product of the number of substituents at each of the other variables.
The [3,5,7]-1H-imidazo[1,5-a]imidazol-2(3H)-one libraries and compounds of Formula I can be prepared according to the general reaction Scheme 1, which for ease of description is shown using single amino acids. The reaction scheme shown forms a single compound or enantiomeric pair of compounds of Formula I. Where libraries are desired, a mixture of amino acids (Boc-R1aa-OH or Boc-R2aa-OH), or carboxylic acids (R3xe2x80x94CO2H) is used for at least one of the coupling steps.
The individual compounds and libraries are prepared using solid-phase techniques. The solid-phase resin, here, p-methylbenzhydrylamine resin (p-MBHA), is indicated in Scheme 1 by the large circle and dash. 
Starting from p-methylbenzhydrylamine (MBHA) resin-bound N-tert-butyloxycarbonyl (Boc) amino acid 1 (Boc-R1aa-OH), the Boc group was removed using a mixture of trifluoroacetic acid (TFA) and dichloromethane (DCM). The resulting amine salt was neutralized, and the resulting primary amine was N-acylated with a second Boc-protected amino acid (Boc-R2aa-OH) as before, to provide the resin bound-monopeptide 2.
Following removal of the Boc protecting group using 55% of trifluoroacetic acid in dichloromethane, the resulting free amine was acylated with a carboxylic acid 3 (R3xe2x80x94CO2H) in dimethylformamide (DMF) using diisopropylcarbodiimide (DICI) and hydroxybenzotriazole (HOBt) to effect coupling. The bicyclic [3,5,7]-1H-imidazo[1,5-a]-imidazol-2(3H)-one 4 was obtained via cyclization using the conditions of Bischler-Napieralski, with 25-fold excess of phosphorus oxychloride (POCl3) in refluxing 1,4-dioxane in the presence of a 30-fold excess of anion exchange resin (AG(copyright) 3-X4) [Bischler, A.; Napieralski, B. Chem. Ber., (1893), 26, 1903; W. M. Whaley, T. R. Govindachari, Org. React., 6, 74 (1951); T. Kametani et al., Tetrahedron, 27, 5367 (1971); G. Fodor et al., Angew. Chem. Int. Ed., 11, 919 (1972); G. Fodor, S. Nagubandi, Tetrahedron, 36, 1279 (1980); idem, Heterocycles, 15, 165 (1981)]. More recent syntheses using freshly distilled POCl3 in the absence of the anion exchange resin have provided yields in the range of about 80 percent. The desired products were readily obtained following cleavage from the resin with anhydrous HF in anisole to provide compound 4.
Following the strategy described in Scheme 1, with the parallel synthesis approach, commonly referred to as the xe2x80x9ctea-bagxe2x80x9d method [Houghten et al., Nature, 354: 84-86 (1991)], libraries are synthesized with 33 different amino acids to provide the R group at R1, 33 different amino acids to provide the R group at R2, and 92 different carboxylic acids to provide the R group at R3, in which the individual building blocks were varied, while fixing the remaining two positions.
Any variety of amino acids can be used with the present invention as described above to prepare a vast array of bicyclic [3,5,7]-1H-imidazo[1,5-a]-imidazol-2(3H)-one with different R1, R2 and R3 groups. As described above, thirty-three first amino acids were coupled to the resin, which amino acids provide the R1 substituent group. The thirty-three amino acids included Ala, Phe, Gly, His(DNP), Ile, Lys(CBZ), Leu, Met, Arg(Tos), Nva, Ser(Bzl), Thr(Bzl), Val, Tyr(CHO), Tyr(BrZ), Nle, Cha, ala, phe, his(DNP), ile, lys(CBZ), leu, met, arg(Tos), ser(Bzl), thr(Bzl), val, trp(CHO), tyr(BrZ), nle, nva, cha.
After the above-described 33 reactions and removal of the BOC protecting group, a single amino acid (valine) was coupled as the second amino acid, thereby providing the R2 group. After removal of the second BOC group, a single carboxylic acid, acetic acid, was coupled to provide the R3 group for the 33 different compounds. Those compounds were thereafter cyclized to form compounds of Formula I and cleaved from the resin.
Another set or sub-library of 33 compounds was prepared by reacting a single amino acid (valine) with the resin to provide one R1 group. After removal of the BOC protecting group, each of the above 33 amino acids was then separately coupled to provide 33 resin-linked peptides with the same R1 group and one of the 33 different R2 groups. On removing the second BOC group, a single carboxylic acid (acetic acid) was bonded to the free amino group to provide a single R3 group for the resin-linked peptides. Theses compounds were also cyclized to form compounds of Formula I, and cleaved from the resin.
In a third set or sub-library preparation, a single amino acid (valine) was coupled to the resin to provide a single R1 group, the BOC group was removed and a second amino acid (valine) was coupled to provide a single R2 group and form a dipeptide. After removal of the second BOC group, the dipeptide was separately reacted with each of the 92 carboxylic acids listed in Table 2, below, to provide 92 different R3 groups. The acylated peptides were thereafter cyclized, cleaved from the solid support resin and recovered. Assays using those compounds are discussed hereinafter.
As used herein, abbreviations for the various amino acid side-chain protecting groups are as follows: xe2x80x9cTrtxe2x80x9d for trityl, xe2x80x9ctBuxe2x80x99 for tert-butyl, xe2x80x9cBocxe2x80x9d or xe2x80x9cBOCxe2x80x9d for tert-butoxycarbonyl, xe2x80x9cTosxe2x80x9d for toluenesulfonyl or tosyl, xe2x80x9cDNPxe2x80x9d for dinitrophenyl, xe2x80x9cBzlxe2x80x9d for benzyl, xe2x80x9cCHOxe2x80x9d for formyl, xe2x80x9cBrzxe2x80x9d for 2-bromobenzyloxycarbonyl and xe2x80x9cCBZxe2x80x9d for carbobenzoxy. As can be seen from the side chains exemplified in the table below, it should be appreciated from the above-described embodiments of R1 and R2 are merely illustrative of the R groups that can be present. Following usual notation, L-amino acids are referred to with an initial capital letter as in Val, whereas D-amino acids are referred to with an initial lower case letter as in ala.
A variety of carboxylic acids can also be used in the acylation step of the reaction of Scheme 1, thereby providing a wide array of substituents at the R3 position of the bicyclic [3,5,7]-1H-imidazo[1,5-a]imidazol-2(3H)-one. Ninety-two carboxylic acids were used in preparing the [3,5,7]-1H-imidazo[1,5-a]imidazol-2(3H)-one libraries. The ninety-two R3 groups were provided by the following carboxylic acids: